Bulk Terminals, SPCC, and the Leak-Proof Concrete Myth: What Every Terminal Manager Needs to Know

Terminal Series – Article three

Contributed by Michael Ellison, Principal/District Manager, PPM Consultants

With over 27 years in the environmental permitting and compliance industry, I’ve seen many challenges that bulk terminal managers face. My work at PPM Consultants, Inc. (PPM) has included bulk terminal compliance, hydrogeologic assessments, remediation system installation, and regulatory negotiations; and I’ve learned that some of the more persistent problems stem not from the complexity of regulations, but from myths that refuse to die. One of the most costly and widespread is the belief that

The Misconception of Impervious Concrete

In the world of bulk terminals—whether you’re storing petroleum, chemicals, or biofuels—the integrity of secondary containment is your last line of defense against spills, regulatory penalties, and long-term environmental liability. Yet, the myth that concrete is “impervious” continues to circulate. This misconception can result in soil, surface water, and groundwater contamination, enforcement actions, and expensive remediation. Let’s break down what regulations actually require, what science and field experience reveal, and why “leak-proof” concrete is more myth than reality.

SPCC Requirements: What You Really Need to Know

The Spill Prevention, Control, and Countermeasure (SPCC) Rule (40 CFR Part 112) sets the standard for secondary containment at bulk terminals. If your facility stores more than 1,320 gallons of oil above ground, you’re subject to the SPCC Rule. The rule requires containment to be “sufficiently impervious” to hold oil until cleanup, with enough capacity for the largest are often used for freeboard calculations. Regular inspection and prompt repair of cracks and joint failures are imperative to ensure secondary containment can function as intended.

Why 1,320 gallons?

The EPA’s SPCC rule applies to facilities with more than 1,320 gallons of above-ground oil storage. The number is roughly equivalent to 31.4 barrels of oil (one barrel equals 42 gallons), a common unit in the petroleum industry. By setting the limit at 1,320 gallons, the EPA ensures that facilities with enough oil to pose a material risk to water resources have proper spill prevention plans in place, while smaller operations with lower storage volumes are not unnecessarily burdened.

Why Concrete Isn’t Leak-Proof

Bulk terminals can be located in harsh environments. , temperature swings, sun/wind/precipitation, chemical exposure, and the sheer volume of stored product all take a toll on concrete. Over time, even the best slabs develop microcracks, especially when exposed to freeze-thaw cycles, heavy equipment, or chemical spills. Common leak paths include shrinkage cracks, expansion/contraction joints, pipe penetrations, and surface spalling. Even a hairline crack can allow oil, fuel, or solvents to migrate into the soil and groundwater.

Both the American Concrete Institute (ACI 350.2-21) and the EPA recommend lining or coating concrete containment with a chemical-resistant barrier. Unlined concrete simply isn’t reliably liquid-tight over time. A 2015 study in Nuclear Engineering and Design found that leakage through concrete is primarily governed by crack width, concrete permeability, and the presence (or absence) of liners. Even small cracks can allow significant leakage, especially under sustained hydrostatic pressure.

EPA Guidance: “Sufficiently Impervious”

Sufficiently impervious doesn’t mean indefinitely impervious.  However, secondary containment (walls and floor) must contain the release until it is cleaned up – that time frame is highly important. If the condition of the slab allows oil to escape in a matter of hours and you can’t respond that quickly, then you’re not in compliance with the SPCC Rule. Furthermore, if inspectors observe leaks or seeps from the basin, or release detection methods indicate a problem, the containment is not considered sufficiently impervious and does not meet SPCC requirements.

Best Practices for Terminal Managers

1. : Use chemical-resistant coatings or liners designed for the stored material and inspect and maintain them regularly.
2. Design for Inspection and Repair: Include accessible joints and sumps, wall/base contacts, slab thickness, and have a plan for periodic integrity testing.
3. Monitor and Document: Install monitoring wells or leak detection systems and keep detailed inspection and maintenance records.
4. Train Staff and Subcontractors: Ensure everyone understands that concrete does not mean leak-proof and provide training on spill response and reporting.

The Science Behind the Myth

It’s not just field experience that debunks the myth of impervious concrete—science backs it up. The American Concrete Institute (ACI 350.2-21) and the EPA both recommend that concrete secondary containment be lined or coated with a chemical-resistant barrier. Why? Because unlined concrete is not reliably liquid-tight over time. The 2015 study in Nuclear Engineering and Design found that leakage through concrete is primarily governed by the presence and width of cracks, the permeability of the concrete, and the presence (or absence) of liners. Even small cracks can allow significant leakage, especially under sustained hydrostatic pressure. These findings reinforce the need for robust design, regular inspection, and the use of chemical-resistant barriers.

Busting the Myth—And How PPM Can Help

For bulk terminals, the stakes are simply too high to rely on the myth of “leak-proof” concrete. The best defense is a combination of smart design, robust coatings or liners, regular inspection, and a healthy dose of skepticism. If you’re responsible for SPCC compliance, ask yourself: When was the last time you inspected your containment for cracks, joint failures, or coating degradation? If you’re unsure, it’s time to take a closer look—before a regulator or a release does it for you.

At PPM, we specialize in helping clients solve complex environmental challenges—from permitting and compliance to remediation and risk management. If you’d like to learn more about how we can help you avoid costly mistakes and ensure your facility is truly protected, contact me at michael.ellison@ppmco.com. Don’t let the myth of impervious concrete undermine your operations—let’s work together to build containment strategies that stand up to real-world conditions.